Generally, a metal air battery has been widely used for a portable device that needs to be used for a long period of time, for example, a hearing aid, and mainly comprises a primary battery. However, recently, there have been attempts to apply the metal air battery to the latest portable electronic devices, such as mobile phones, PDAs, or notebook PCs, communication devices for military use, and large-capacity charging devices. As such, the availability of the metal air battery has been gradually increasing.
Such a metal air battery uses oxygen contained in air as an anode active material, and uses metal as a cathode active material. The metal air battery includes a separator between the anode and the cathode, thus isolating the anode and the cathode from each other, preventing short-circuiting of current due to the contact between the electrodes, and enabling the passage of metallic ions. The flow of electrons is implemented by an oxidation-reduction reaction between the oxygen and the metal, and the metal used as the cathode is usually immersed in electrolyte in the form of powder.
A conventional metal air battery has a button-type or a coin-type structure which is constructed so that an air cathode is placed in the battery in the form of a flat plate, so that the battery may be restrictively used for a device such as a hearing aid. However, practically, the utilization range of a cylindrical battery is wider. In order to solve the problem, there has recently been active research conducted into a cylindrical metal air battery.
As the prior art, there are Korean U.M. Registration No. 20-0414801, Korean Patent No. 10-0883934, Korean Patent No. 10-0875105, etc., which deal with a cylindrical air-zinc battery.
However, the conventional cylindrical air-zinc battery is problematic in that external air always flows into the air cathode, so that the natural electric discharge of the battery occurs even when the battery is not in use, and thus the storage performance of the battery deteriorates.